Other Parts Discussed in Thread: LM7301, INA250, INA301, INA200, INA139, INA199
We are trying to design a device for detecting a specific and configurable current value threshold, capable to generate a interruption in our MCU and wake up it.
(F1_GeneralSch) We have a 2-wires preassure sensor powered by 12v whcih provide a current value between 4-20 mA. Once our MCU has wake up, it must measure the current value on the line sensor so this current value MUST NOT be modified.
We are thinking on a detection system divided in 3 different states (F2_DetectionCircuitSch), but we dont know if you can provide a specific standard solution to cope with our porpuse directly, or cope with some of these different parts separatly.
Our first approximation (F3_DetectionCircuitSimulation)to the detection device is componed using ideal operational amplifiers: but we dont know how to select the correct elements and configuration values, because we had simulated it with ideal OA´s, but its possible unreach this features.
1- Using Rshut to convert current-voltage values without current sensor line modification. I=4mA -> Vrshut = 399.8mV || I=20mA -> Vrshut = 2v
2- We want adapt/convert Rshut voltage to a more suitable voltage range to make comparation easier (next stage), without reach saturation value on the OA.
Vrshut=399.8mV -> Vout=1.2v || Vrshut=2v -> Vout = 6v || GAIN = 3.
We dont know if these 2 stages could be done using INA250-Q1.
3- Final stage made up with a comparator in which threshold value is set by Vref voltage (manuallyconfigurable using a potenciometer) . This stage is easiest because we have added the previous voltage adaptation stage.
For this part, we would use a LM293P or LM7301 with a voltage divider to set up Vref.
Do you have any integrated solution or aproximation to this device? Do you have any other circuit to cope with each stage separately?
It´s really important for us to minimize consumption on circuit elements.